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Detection of corneal ectasia using corneal tomographic and biomechanical assessment

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Session Details

Session Title: Medical Cornea & Biomechanics

Session Date/Time: Sunday 23/09/2018 | 08:00-10:00

Paper Time: 09:03

Venue: Room A3, Podium 3

First Author: : S.Koh JAPAN

Co Author(s): :    R. Ambrosio, Jr.   R. Inoue   N. Maeda   A. Miki   K. Nishida        

Abstract Details


To test the accuracy for detecting corneal ectasia with corneal tomography and biomechanical assessments in Japanese population.


Osaka University Hospital, Osaka, Japan


Criteria for normality and keratoconus diagnosis were based on a comprehensive ophthalmic examination, including Placido-disk corneal topography (TMS-5; Tomey; Aichi, Japan). One eye randomly selected from 71 keratoconus (KC) patients and from 70 normal controls were enrolled along with thirteen eyes with normal topography from patients with very asymmetric ectasia (VAE-NT), and their respective nine non operated ectatic eyes (VAE-E). Pentacam HR and Corvis ST (Oculus GmbH, Wetzlar, Germany) parameters were analyzed, including Belin/Ambrósio Deviation (BAD-D), Corvis Biomechanical Index (CBI) and Tomographic and Biomechanical Index (TBI). Their accuracies for detecting ectasia were assessed considering receiver operating characteristic (ROC) curves.


Considering normals versus frank ectasia (KC + VAE ectasia), the areas under the ROC curves (AUROC) for BAD-D and TBI were 1.0, and for CBI was 0.977, having no significant differences (De Long, p>0.05). The BAD-D cut-off value 2.2 provided 100% sensitivity and specificity. The TBI cut-off 0.591 provided 100% sensitivity for frank ectasia, with 98.57% specificity. All VAE-NT eyes had normal topography, including Kmax lower than 45D. 7 VAE-NT eyes (53.8%) were abnormal based on current published criteria for ectasia susceptibility, including TBI higher than 0.23 (46.1%), BAD-D higher than 1.45 (30.7%), or CBI higher than 0.5 (30.7%).


Corneal tomographic and biomechanical indices are highly sensitive and specific to distinguish frank ectatic from normal healthy eyes. The integration of data, such as in the TBI, enhances the ability to detect abnormality in most eyes with normal topography from VAE cases, and in rare normal cases. While keratoconus is defined as a bilateral disease, some of the VAE-NT cases may truly represent unilateral ectasia, possibly related to environmental factors. The TBI may represent the inherent susceptibility for ectasia progression. Larger population studies are needed including longitudinal evaluation.

Financial Disclosure:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, ... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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